Direction finder



March 22, 1932. P. SCHWERIN l ,DIRECTION FINDER Filed Nov. 2, 1929 m/ TQ aumento@ Patented Mar. 22, 1932 UNITED y STATESl PAT-ENT OFFICE PAUL SCHWERIN, or mr'rEEnEoED, NEW JERSEY, AssIGNoE ro PEERYMAN JiILEC'IEsIok i Co. INC., or NORTH BERGEN, NEW JERSEY, A CoRORATIoNoE DELAWARE i DIRECTION EINDEB Application led November This invention relates to direction finders for aircraft, ships or other vehicles and has for an object a direction finder which is sim plein construction, effective inoperation and contains no moving parts. y

A direction finder embodying this invention comprises a vacuum tube oscillator having co-acting induction coils in its input and output circuits in combination with means lo for vconcentrating lines of force from the earths magnetic iield and producing a magnetic field substantially coaxial with said coils. The coils are mounted on an aircraft or the like in fixed relationship to the longitudinal axis thereof and preferably `have their'axes parallel to the crafts axis. In the output circuit of the oscillator there is provided a meter whichindicates changes in current flow in such circuit. The current flow in the output Circuit willbe varied by changes in the strength of the magnetic eld applied to the current, the eld in turn being varied with changes in direction of the axis of the craft. By reading the meter the deviation of the. crafts axis from the direction of the earths magnetic iield'may be determined and the angularity of the path lof travel of the craft relatively to the earthls magnetic field be thereby established. f

Other objects, novel features and advantages of this invention will be apparent from the following description and accompanying drawing, wherein: t e single fi ure discloses partly in section and partially iagrammatic an embodiment of the invention. In the drawing a glass envelope 10 0r the like isprovided with a re-entrant stem 11 in 4 which are sealed two pairs of leading-in wires 12 and 13. The inner ends of the leading-in wires 12 and 13 support induction coils 14 and 15, while the outer ends are connected to terminals mounted in the base 16 which supports the envelope 10. "`A vacuum tube oscillator circuit is shown at 17 and the coils 14 and 15 are so connected with the electrodes of the vacuum tube 18 through thevterminals 1 5 that such ,coilsv constitute the feed back for the oscillator cirlcuit. The vacuum electrode 18 is ofv the Vstandard vthree-electrode type and electrical viation fof the craft from the :desi-redcour's 2, 192s. serial No. 404,466.

energy is supplied thereto in the usual manner from suitable source yof electrical ener such, for example, as the batteries A and In the input circuit there is provided the variable condenser 19 usual to such Circuit and in the output circuit there is provided a meter 20 which registers the value of the current flowing in such circuit.

The coils 14 and 15 are Co-axially arranged and a pair of alined spaced pole pieces 21 are arranged with their axis co-incident with the axis of the coils. These pole pieces are composed of metal which has high magnetic permeability at low flux density and which yis devoid of permanent magnetism. These pole pieces'are effective to concentrate the lines of force of the earths'magnetic field to produce a strong field passing through the coils 14 and 15. VThe strength of this field will be dependent upon the position of the pole pieces relative to the earths magnetic field. 'The field in the coils 14 and 15 will be maximum when the pole pieces 21 are `parallel with the earths magnetic field and there will be no field when the pole pieces are perpendicular to the e'arths magnetic field.

The ow of'current'ingthe output circuit ofthe oscillator will vary inresponse to the',

strength of the `field-produced through the' i coils 14 and 15 by the pole pieces 21.-`- It is' thus possible by observing the meter 20 gto' determine whether the rfpolefpieces 21 are inv alinement with the earths magneticV field or are transverse thereto. `llVhen the vessel 1Q is mounted upon an aircraft or other vehicle',-` A the'pole pieces 21 are given a definite direcl tionv with respectt to the longitudinal axis ofthe craft, preferably parallelxthereto. 4'The l meter 2O is mounted at any suitable location A where it is plainlyvisible to the pilot and deh can beY readily ascertained ',byl observation the meter. The oscillator may be adjustedlfso that an extremely slight variation in-thefield duek to` slight variation in direction ywould lcause a spill-over similar tog-.that experienced in 'radio sets when oscillaticn-rfstarts fand squealing begins. rllhe pointerof'the-met'er under such circumstancesfwould jump-install! I vtaneously from a low to a high reading and would 've a very definite indication of variations in direction.

Although this device has been disclosed primarily for use in connection with "the earths magnetic field, it is well adapted for use in connection with a radio beam. The

meter would show one reading when the coilsl were in alinement with the radio beam and another reading when they were out of alinement with such beam. eviation from the direction of the radio beam is instantly indicated by the meter andthe pilot need only to maintain his direction such that the meter reading remains constant. Itvwill then be flying alon the radio beam. Although the coils 14 an 15 are shown as being arranged within a container it is not necessary that they be so enclosed. The container merely protects the coils, `but in no way affects the operation of the set. The enclosure for the coils may be dispensed with and the set will function equally well.

It is of course understood that various modifications may be made in the device above described, without in any way departing from the spirit of the invention as defined in the appended claims.

I claim:

1. A direction finder comprising a vacuum tube oscillator having co-acting induction coils in its input and output circuits, and means for concentratingr the horizontal components of the lines of force of the earths magnetic field and directing the same through said coils. n

2. A direction finder comprising a vacuum tube oscillator having co-acting induction coils in its input and output circuits, means for concentrating the horizontal components of the lines of force of the earths magnetic vfield and directing the same through said coils, and means for indicating variations in the current flow in the output circuit.

8. A direction finder comprising a vacuum Atance connection between said input and output circuits.

6. A direction finder comprising a vacuum tube oscillator havingv itsinput and output circuits inductively connected, means for concentratin the horizontal components' of the lines of orce ofetlie earths magnetic'field 4 electrode vacuum tube, an input and an output circuit for saidA tube, an inductive connection between the input and output circuits,

and means for concentrating the horizontal components of the lines of force of the earths magnetic field and directing the same through said induction connection.

8. A direction finder comprisingf'a threeelectrode vacuumtube, an'inputand an output circuit for-said tube, an inductive connection between the input and'output circuitsmeans for concentrating same and directing the same through said induction connection, and means for indicating variations of current flow in said output circuit.

9. A direction finder comprising a vacuum' tube oscillator having an inductive connection between its in ut and output circuits and pole pieces of high magnetic permeability at low flux density operatively related to said inductive connection.

In testimony whereof, I have signed my name to this specification.

PAUL SCHWERIN.

tube oscillator having co-acting induction' coils in its input and output circuits, and pole pieces substantially co-axial with said induc-` tion coils, said pole pieces being composed A of a metal having high magnetic permeability at low flux densit 4'. A direction n er comprising a vacuum tube oscillator having co-acting induction coils in its input and output circuit, pole pieces substantially co-axial with said induction coils, said pole ieces being composed of a metal having hig magnetic permeability at low flux density, and means for indicating variations in the current fiow in said output circuit. 5

5. A direction finder comprising a vacuum iis tube oscillator having its input and output circuits inductively connected, and means for concentrating the horizontal components of the lines ofl force of the earth s magnetic field and directing the same through the induc- 

